Conventional electric vehicles carry a fuel cell as a power supply for driving a vehicle and a fuel, which is hydrogen or a raw fuel for generating hydrogen, to operate the fuel cell to generate electricity.
When hydrogen itself is loaded on a vehicle, the hydrogen gas is compressed and charged into a high-pressure cylinder, or liquefied to be filled in a tank, or loaded on a vehicle by using a hydrogen-absorbing alloy or a hydrogen-adsorbing material. However, the high-pressure container has a relatively small capacity, resulting in a smaller hydrogen charging amount, even though it requires a greater wall thickness. A liquefying charging method using liquefied hydrogen is inevitably accompanied with vaporization loss, and demands greater energy for liquefaction of the hydrogen gas. The hydrogen-absorbing alloy or hydrogen adsorbing material does not have a sufficiently high hydrogen-storing density necessary for electric vehicles and the like, and control of absorption and/or adsorption of hydrogen is also difficult. Although it is also possible to use a method of obtaining hydrogen by steam-reforming a raw fuel, the reforming reaction is an endothermic reaction, and therefore, additional heat source is required. Accordingly, it is not possible to improve the overall energy efficiency in a system employing an electric heater or the like as a heat source. Thus, it is necessary that a quantity of hydrogen can be stably secured under various environmental conditions.
A method of supplying hydrogen is yet to be technically established, and it is desired that such a hydrogen-supplying method be established, in light of the expected increase in utilization of hydrogen in various apparatuses in the future.
As technology relevant to the above, a fuel cell system having a reforming apparatus in which a steam-reforming reaction for a fuel by using a catalyst, which is an endothermic reaction, and a regeneration reaction of recovering the temperature of the catalyst reduced by the steam-reforming reaction, are alternatively switched therebetween has been proposed (e.g., see U.S. Patent Application Publication No. 2004-175326).
Other methods have been disclosed in connection with this technology (e.g., see U.S. Patent Application Publication Nos. 2003-235529, 2004-170558, and 2004-170559). In addition, a fuel cell using a hydrogen-permeable material has also been disclosed as an example of a fuel cell generating power in high temperature regions (e.g., Japanese Patent Application Laid-Open No. 2004-146337).